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Questions and Answers
What is the main function of the electron transport chain (ETC)?
What is the main function of the electron transport chain (ETC)?
Isocitrate dehydrogenase converts a-ketoglutarate into succinyl-CoA while producing NADH.
Isocitrate dehydrogenase converts a-ketoglutarate into succinyl-CoA while producing NADH.
False
What do NADH and FADH2 donate to the electron transport chain?
What do NADH and FADH2 donate to the electron transport chain?
Electrons
The enzyme that catalyses the conversion of succinate to fumarate is called __________.
The enzyme that catalyses the conversion of succinate to fumarate is called __________.
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Match the enzymes with their corresponding reactions in the citric acid cycle:
Match the enzymes with their corresponding reactions in the citric acid cycle:
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What is the primary product of glycolysis?
What is the primary product of glycolysis?
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Glycolysis occurs in the mitochondria and requires oxygen to proceed.
Glycolysis occurs in the mitochondria and requires oxygen to proceed.
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What is the key regulatory enzyme in glycolysis?
What is the key regulatory enzyme in glycolysis?
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The reaction catalyzed by _______ converts glucose into glucose-6-phosphate.
The reaction catalyzed by _______ converts glucose into glucose-6-phosphate.
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Match the following components of cellular respiration with their roles:
Match the following components of cellular respiration with their roles:
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Which of the following statements best describes the citric acid cycle?
Which of the following statements best describes the citric acid cycle?
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ATP is only produced in the oxidative phosphorylation stage of cellular respiration.
ATP is only produced in the oxidative phosphorylation stage of cellular respiration.
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How many molecules of CO2 are produced for each Acetyl-CoA during the citric acid cycle?
How many molecules of CO2 are produced for each Acetyl-CoA during the citric acid cycle?
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Study Notes
Cellular Respiration
- Eukaryotic cells utilize a multi-step process to convert glucose into ATP, a usable energy form.
- This process occurs primarily in the cytoplasm and mitochondria.
- Three main stages: Glycolysis, Citric Acid Cycle, and Oxidative Phosphorylation.
- Enzymes are crucial for regulating and catalyzing reactions, ensuring efficiency.
- Understanding cellular respiration is vital for advancing therapies for mitochondrial diseases.
Glycolysis
- First stage of cellular respiration, taking place in the cytoplasm.
- Breaks down one glucose (6C) molecule into two pyruvate (3C) molecules.
- Anaerobic process - does not require oxygen.
- Two phases: investment and payoff.
- Investment phase:
- Uses 2 ATP to phosphorylate glucose and fructose-6-phosphate.
- Hexokinase catalyses the phosphorylation of glucose into glucose-6-phosphate trapping it in the cell.
- Phosphofructokinase is a key regulatory enzyme, activated by AMP, inhibited by ATP.
- Payoff phase:
- Further metabolizes 2 3C molecules, yielding 4 ATP and 2 NADH.
- Pyruvate kinase catalyses the conversion of phosphoenolpyruvate to pyruvate.
- Enolase removes a water molecule, causing a double bond formation.
- Forms 2 ATP per glucose.
- With oxygen present, pyruvate is transported to mitochondria for further oxidation.
Citric Acid Cycle (Krebs Cycle)
- Completes the oxidation of Acetyl-CoA.
- For each Acetyl-CoA, produces 3 NADH, 1 FADH₂, and 1 GTP (converted to ATP).
- Releases 2 CO₂ as waste products.
- Key enzymes:
- Citrate synthase: Condenses acetyl-CoA and oxaloacetate to form citrate.
- Isocitrate dehydrogenase: Oxidizes isocitrate to α-ketoglutarate, reducing NAD+ to NADH, releasing 2 CO₂.
- α-ketoglutarate dehydrogenase: Converts α-ketoglutarate to succinyl-CoA, reducing NAD+ to NADH, releasing CO₂.
- Succinate dehydrogenase: Oxidises succinate to fumarate, reducing FAD to FADH₂.
- FADH₂ carries high-energy electrons to the electron transport chain.
Oxidative Phosphorylation
- Final stage, occurs in the inner mitochondrial membrane.
- Two stages: electron transport chain (ETC) and chemiosmosis.
- NADH and FADH₂ donate electrons to the ETC, a series of protein complexes and electron carriers.
- Electrons release free energy as they move through the ETC, driving proton (H⁺) pumping into the intermembrane space.
- ETC Complexes:
- Complex I (NADH dehydrogenase): Oxidises NADH, transfers electrons to ubiquinone (Q), pumps protons.
- Complex II (Succinate dehydrogenase): Transfers electrons from FADH₂ to Q, does not pump protons.
- Complex III (Cytochrome bc₁ complex): Passes electrons from QH₂ to cytochrome c, pumps protons.
- Complex IV (Cytochrome c oxidase): Transfers electrons to oxygen, the final electron acceptor, forming water.
- Chemiosmosis:
- ATP synthase uses the proton gradient to synthesize ATP from ADP and inorganic phosphate.
- Oxidative phosphorylation produces the majority of ATP (approximately 26-28 per glucose).
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Description
Explore the intricate processes of cellular respiration, focusing on glycolysis as the first stage. Understand how eukaryotic cells convert glucose into ATP through glycolysis, the role of enzymes, and the significance of this process in cellular metabolism. This quiz will enhance your knowledge about energy production and regulation within cells.
